US 3153458 A
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Description (OCR text may contain errors)
Oct. 20, 1964 Filed 00b. 8, 1962 Era- 1 L. W. SHORT BLADE-TYPE DRILL BIT 2 Sheets-Sheet 1 INVENTOR.
ATTORNEYS Oct. 20, 1964 L. w. SHORT BLADE-TYPE DRILL BIT 2 Sheets-Sheet 2 Filed Oct. 8, 1962 ATTORNEYS United States Patent 3,153,458 BLADE-TYPE DRILL BET Lot William Short, Dallas, Tex assignor to Drilling & Service, Inc, Detroit, Mich, a corporation of Delaware Filed (let. 8, i962, Ser. No. 228,998 9 Claims. (til. 175-329) This invention relates to a blade-type drill bit and more particularly to a drill bit using hard, abrading elements, such as diamonds, largely confined to and arranged along blade-like projecting ribs to form the cutting edges of the bit. Other portions of the working surface of the bit are provided that are free of abrading elements and that, in general, conform in contour to such ribs but are radially inwardly olfset from said cutting edges to provide bumper or abutment portions that by contact with the earth formation during the drilling operation determine the amount of bite taken'by such cutting edges during rotation of the bit.
In accordance with my present invention, the working face of the bit is provided with a plurality of Water grooves that extend from near the mid portion of the lower working surface of the bit radially outwardly and upwardly, and the diamond-embedded cutting edges are formed along corresponding edges or" each of several such water grooves, such edges being herein termed the leading edges. The other edges of the respective water grooves, which edges are herein termed the trailing edges, are left free of abrading particles and constitute the bumper or abutment portions previously referred to. The bumper portions, in addition to controlling the bite of the cutting edges, function to direct the drilling fluid along the cutting edges and, in combination with properly designed and arranged water courses, serve to insure high velocity of the drilling fluid and thereby increase the efliciency of the fluid in bottom scavenging and in the removal of earth. formation cuttings.
A blade-type drill bit embodying the features of construction and functioning in the manner similar to that just described is disclosed and claimed in my pending application for patent Serial No. 195,595, filed May 17, 1962. The drill bit of my present invention, however, distinguishes from the drill bit construction therein disclosed in that the lower working end of my present drill bit is generally sperical, or ball-shaped, in contour. This insures better load distribution over the working face of the bit during the drilling operation. As is well known, the average drill collar string used in rotary drilling is a long slender string that will buckle and become unstable under the effects of columnar loading, such that at any given instant during a revolution of the bit, a small area on one side of the working face of the bit is obliged to carry most of the load. This is particularly true if the axis of the bottom drill, revolves about the axis of the hole being drilled. Where, however, the lower working face of the drill bit is substantially sperical, or ballshaped, such localized overloading of an area of the Working surface is much less likely to occur under sim lar circumstances.
It is therefore an important object of this invention to provide a drill bit of a blade-type construction that possesses novel operational advantages in the drilling of bore holes in various types of earth formations.
It is a further important object of this invention to provide a drill bit of improved construction in which there is a more efl'icient utilization in operation of high velocity streams of drilling'fiuid both with respect to the cooling of the abrading elements in the cutting edges of the bit and also in the removal of the earth formation cuttings formed during the drilling operation.
It is a further object of this invention to provide, in a drill bit, a lower portion of the bit that is generally sperical, or ball-shaped, in contour, and that is provided with a plurality of water grooves extending outwardly and upwardly from near the mid-point of the lower surface of the bit, and that is further provided along leading edges of a plurality of such water grooves with cutting edges substantially continuous in extent with such grooves, and along the other, or trailing edges of the same grooves is provided with non-cutting surfaces that are slightly oilset axially upwardly and/ or inwardly to function as bumper or abutment portions, the trailing edges in cooperation with the leading edges defining the bite taken by the cutting edges of the bit during revolution thereof.
Other objects, features and advantages of this invention will become apparent to one skilled in the art from the following description of the embodiments of the invention illustrated in the accompanying drawings, in which:
FIGURE 1 is an elevational view of a drill bit embodying the features of my invention;
FIGURE 2 is a bottom plan view of the bit, rotated slightly from its position in FIGURE 1;
FIGURE 3 is a sectional view taken substantially along the broken line III-J11 of FIGURE 2;
FIGURE 4 is an enlarged fragmentary sectional view taken along the line IV--IV of FIGURE 1; and
FIGURE 5 is an enlarged fragmentary sectional View taken along the line VV of FlGURE 2.
As shown on the drawings:
The drill bit illustrated in the drawings is one adapted to be attached to the lower end of a drill stem in the drilling of oil wells and the like, wherein the drill stern (not shown) is rotated by a rotmy table (not shown) and wherein the drilling fluid, such as any of those commonly used for the purpose, is circulated down through the drill stem and discharged through the lower Working end of the drill bit. The drilling fluid serves the purpose of cooling the abrading elements of the bit and of carrying away from the bottom of the bored hole the particles of earth formation generated by the abrading action of the drill bit or otherwise present in the bottom of the hole. As is Well understood, the drilling fluid is usually a water suspension of a clay, or mud, and is pumped down through the drill stem to the drill bit under considerable pressure. As will be explained hereinafter in greater detail, the particular construction and arrangement of the fluid discharge bores and water grooves in the bit of my invention, in combination with the configuration of the working face of the bit and the constriction of the Water grooves toward the periphery of such Working face, results in a higher velocity flow of drilling fluid over and across the abrading elements during their cutting action than has heretofore been usually the case.
With more specific reference to the drawings, the reference numeral ltl indicates generally a drill bit of my invention, provided at its upper end with a cylindrical shank 11 having a bore 12 therethrough. While bits of the type here under consideration may be either internally or externally threaded for attachment to the drill stem, the present embodiment is here illustrated as internally threaded, and the external surface of the shank 11 is provided with wrench-engaging depressions 13 to facilitate the threading operation. The shank ii is thus hollow and is provided with internal threads 14 for attachment to the drill stem.
The body of the bit, indicated at 15, is carried at the lower end of the shank 11, sometimes integrally therewith and sometimes rigidly attached thereto in any suitable manner. Said bit body 15, so far as its general contour is concerned, is substantially spherical both in bottom plan view and in elevation, although the centers of curvature for the two sets of surfaces involved need not be exactly coincident along the axis of shank and bit body. In bottom plan view, as in FIGURE 2, the circularcontour of the substantially spherical lower portion of the bit is indicated by the reference numeral 16 and for the generally spherical lower portion of the body of the bit shown in elevation in FIGURE 1, by the reference numeral 17. The upper portion of the bit body 15 has an outer cylindrical surface 18 of slightly larger diameter than either the transverse diameter of the lower portion of the bit or the diameter of the shank 11, with a sloping surface or shoulder 19 extending between the cylindrical portion 18 of the bit and the lower cylindrical portion of the shank 11.
As best shown in FIGURE 2, the drill bit body 15 is provided with a plurality of water courses, or grooves, four in all in the embodiment there illustrated. Depending upon the size of the bit, more or fewer water courses might be employed, but four water courses are preferred for a bit having an outside diameter of about 9 or 10 inches. The four water courses illustrated are designated, respectively by the reference numerals 20, 21, 22 and 23, the bottom surfaces of which are constituted by portions of the generally spherical surfaces that includes the circle shown in plan view (FIGURE 2) and indicated by the reference numeral 15. Said waterways, or grooves, 20, 21, 22 and 23 are relatively deep and extend outwardly from near the midpoint of the lower surface of the bit and upwardly along the perimeter past the enlarged cylindrical portion 18 at the upper portion of the bit body 15. Each of said grooves is of substantial depth and the depths of the several grooves are substantially the same, but the cross sectional areas of the respective grooves vary one from another and also vary along their respective lengths. In the case of three of the water grooves, which will be termed the main water grooves, identified by the reference numerals 21D, 21 and 22, the leading edges 24, 25 and 26 thereof extend substantially radially outwardly, as viewed in FIGURE 2, and extend upwardly, across the height of the enlarged cylindrical surface 13, to the sloping surface 19, as shown in the case of the water groove 20 in FIG- URE 3.
Each of said leading edges 24, 25 and 26 being generally of similar construction and arrangement, it should sulfice to describe only the leading edge 25, since that edge is more fully described in the drawings. Said edge 25 (FIG- URE is defined by the generally plane wall 27 of a sintered tungsten carbide insert, or blade B, forming a wall of the groove 21, and an external surface 28 of said blade B forming a continuation of the external generally spherical working face of the bit body 15. The blades B, three in number, are separately formed of sintered tungsten carbide With diamonds embedded in the edges that are to form the cutting edges 24, 25 and 26, and these blades are then inserted in the mold in which the bit is formed. In this Way diamonds D, or other abrading particles, are set substantially continuously along the entire arcuate extent of the edges of the blades B to convert said edges into cutting edges, or ribs. As shown in FIGURES 1 and 3, the edge 25, extends upwardly through the annular cylindrical enlargement 18 and the diamonds D are embedded continuously therealong, preferably in a single row, or in not more than two or three rows, except along the annular portion 18 where the diamonds are set over a widened area to provide lateral reaming surfaces L.
The portion of the external working surface of the bit body 15 that lies on the opposite side of the water groove 21 from the surface 28 provides-what is herein termed a bumper or an abutment surface 30. The edge of the bumper surface 31 at the groove 21 constitutes the trailing edge 31 of said bumper surface. Said bumper portion 36 extends upwardly until it merges with the generally cylindrical surface 18. The trailing edge 31 is offset radially and/or axially-inwardly of the leading edge 25 formed along the insert or blade B throughout substantially their .5- full extents. The amount of said offset is illustrated in FIGURE 5 by the reference letter D and is substantially the same throughout the extents of the leading edge 25 and the trailing edge 31. It is this amount of offset that determines the bite taken by the leading edge 25 of the rib 29, as will be more fully explained hereinafter.
With further reference to the water groove 21, it will be noted that said groove is of varying width along the lower generally spherical portion of the bit body, being wider at approximately the mid portion thereof, as indicated. by the letter W than it is either at its inner end I or its outer end 0. A water bore 32 opens into the wider portion W of said water groove 21. Said bore 32 extends through the body 15 of the bit from a counterbore 12a (FIGURE 3) forming a continuation of the bore 12 of the shank 11. Thus, drilling fluid can be pumped down through the drill string and the hollow shank into the bore 32 for discharge into the water groove 25. Similar water bores 33 and 34 are provided for discharging drilling fluid into the water grooves 22 and 20, respectively. All of said bores 32, 33 and 34 are restricted at their discharge ends to provide jets I. Said water grooves 21 and 22, like the water groove 21, are wider near the mid portions of their lower extents and are restricted as they continue upwardly along the lateral face of the bit body.
In the case of the protuding rib or cutting edge 25, said edge extends inwardly beyond the center of the lower surface of the bit as represented by the reference letter C (FIGURE 2) lying on the true axis of the bit body 15. The extension of the cutting edge 25 beyond the center point C insures an effective cutting action across the axis of the hole being drilled and eliminates the existence of any dead spot such as would occur if all of the cutting edges terminated short of the center point C or passed directly through said center point. By virtue of its extension beyond the center point C and slightly offset therefrom, the cutting edge 25 exerts a cutting action across the corresponding center point of the bottom of the hole being bored. The corresponding cutting edges 24 and 26, respectively, are shorter than the cutting edge 25 and terminate at their inner ends well short of the true center C. However, like the cutting edge 25, the edges 24 and 26 are offset axially and/or radially outwardly from the corresponding trailing edges 37 and 33 of the water grooves 20 and 22, respectively, by the same amount of offset as that represented by D between the cutting edge 25 and the trailing edge 31 (FIGURE 5).
In the illustration of my invention there are, therefore, three main water grooves, namely water grooves 20, 21 and 22, and the same number of corresponding sets of cutting edges 24, 25 and 26 paired with corresponding trailing edges 37, 31 and 38 of bumper portions 40, 30 and 42. These bumper portions are free of abrading particles. The bumper portions 30 and 42 are continuous portions of the external working surfaces on which are formed the cutting edges 24 and 25, respectively, while the bumper portion 40 is a fragmentary portion of the external surface that is isolated from the other external surface portions of the lower part of the bit by the water grooves 20 and 23. The Water groove 23 also differs from the other water grooves in that it has a relatively short, narrow inner portion, or throat T, from which it flares laterally outwardly over the generally spherical surface S of the bit body 15 and continues upwardly along the lateral more or less cylindrical extension CE thereof (FIG. 1).
By virtue of the construction thus far described, there are three areas that might be termed jet areas in each of the three main waterways 21), 21 and 22. The waterway 23 is without any jet area, since, unlike the other waterways, there is no bore leading directly into the waterway 23. The drilling fluid discharged through the bores 32, 33 and 34 is directed mainly outwardly and upwardly along the respective Water courses 21, 22 and 20 into the annulus between the outside diameter of the shank 11 and the drill hole wall. Some of the drilling fluid flows inwardly from the respective bores 32, 33 and 34 toward the lower central portion of the bit and outwardly through the throat T into the low pressure waterway 23 and thus outwardly and upwardly between the drill bit shank and the wall of the hole being drilled.
In operation the drilling action of the bitris substantially as follows: when sufficient weight, or load, is applied to the bit, the cutting edges provided by the diamondset ribs 24, 25 and 26 bite into the earth forma-. tion to the depth, approximately that represented by the reference numeral D, permitted by the relatively large cross-sectional areas of the'bumper or abutment portions 40, 30 and 42. The latter come into contact with the earth formation at the bottom of the hole being drilled and prevent further penetration of the cutting edges into the formation. As the bit is rotated 120 there will be a penetration or removal of formation corresponding to the extent of the controlled bite. The formation so out, or abraded, is discharged quickly through the waterways 20, 21, 22 and 23.
The fluid flow pattern, with the blades sunk into the formation and with the bumper areas in contact with the bottom of the hole is as follows: the fluid is delivered through the three jet nozzles I represented by the discharge ends of the bores 32, 33 and 34 into the respective jet areas of the water grooves 21, 22 and 20. In operation, the jet velocity of the drilling fluid so discharged through the discharge ends of said bores 32, 33 and 34 is approximately 500 feet per second. The jet streams are deflected in directions initially determined by the walls of the waterways 20, 21 and 22 over the bottom surfaces of said waterways and upwardly along the lateral surfaces thereof and thence into the annulus between the drill shank and the wall of the hole. In usual operation the fluid velocity of the drilling fluid is never less than about 200 feet per second, the minimum velocity being along the bottom of the hole inwardly of the discharge openings of the bores 32, 33 and 34.
As previously pointed out, owing to the ball-shaped contour of the lower portion of the bit body 15, the load on the drill string is more equally distributed over the working surface of the bit than where bits are used having non-spherical working surfaces. By comparison with other contours of drill bits it has been found that the load distribution is best when a ball-shaped bit contour is used.
I claim as my invention:
1. A drill bit comprising: a bit body having at its upper end an axial recess and at its lower end a working face, said working face including an upper generally cylindrical annular reaming portion and a generally spherical lower surface portion of lesser transverse diameter than said annular portion, said working face being formed with a plurality of water grooves extending from near the midpoint of said lower surface portion to the periphery thereof and upwardly through said annular portion, the
working face along corresponding leading edges of respective grooves projecting outwardly beyond the trailing edges of said respective grooves for substantially the full extents of said grooves over said lower surface portion to provide ribs, abrasive particles embedded in and along said ribs to constitutecutting edges, said trailing edges 7 cutting edges extends along an are that terminates beyond and is .slightly offset from the projected axis of said spherical portion to effect a cutting action across said projected axis.
3. Adrill bit comprising: a hollow cylindrical shank, a bit body at the lower end of said shank having an axial recess forming a continuation of the hollow in said shank, said bit body having an upper annular working face portion of larger diameter than said shank and a lower generally spherical working face portion of lesser transverse diameter than said annular portion, there being a plurality of relatively deep water grooves extending from near the midpoint of said lower spherical portion outwardly thereof and upwardly through said annular portion, said grooves being in open flow communication near said midpoint to form continuous water flow passages thereacross, said working face portions along correspondingly leading edges of some of said grooves projecting outwardly of the respective trailing edges of said grooves a substantially uniform distance for substantially the full extents of said grooves over said lower generally spherical working face portion to provide ribs continuous therealong, abrasive particles embedded in and along said ribs to form cutting edges, said trailing edges and adjacent working face portions being free of abrasive particles and functioning during the drilling operation as abutments to determine the depth of the bite taken by said cutting edges, there being bores extending from said axial recess through said bit body into some of said grooves to discharge drilling fluid thereinto for passage along said groves and upwardly past said shank during the drilling of a hole in an earth formation.
4. A drill bit as defined in claim 3 wherein there are three water grooves each provided with a bore for the discharge of drilling fluid thereinto, and there is a fourth water groove directly opposite one of said three water grooves but having no bore provided for discharge directly thereinto, said fourth groove discharging outwardly over an enlarged upwardly flared area provided by a segmental spherical surface lying inwardly of said generally spherical working face portion.
5. A drill bit as defined in claim 3, wherein each water groove having a bore for discharging drilling fluid thereinto is abruptly constricted in cross section outwardly of the opening therein of such bore.
6. A drill bit as defined in claim 3, wherein each of said bores is smoothly and abruptly restricted at its lower end to provide a jet discharge opening into its corresponding water groove.
7. A drill bit as defined in claim 4, wherein each water groove is restricted at its inner lower end and those water grooves provided with bores discharging directly thereinto are also restricted in cross-sectional area outwardly toward the lateral periphery of said bit.
8. A drill bit as defined in claim 3, wherein one of said cutting edges extends inwardly past and offset from the true axis of said bit.
9. A drill bit as defined in claim 3, wherein each of said cutting edges is provided by a relatively narrow, elongated, sintered tungsten carbide insert having diamonds set continuously along an edge thereof to provide a cutting edge.
References Cited in the file of this patent UNITED STATES PATENTS 2,009,742 Mitchell July 30, 1935 2,186,725 Hughes Jan. 9, 1940 2,371,489 Williams Mar. 13, 1945 2,371,490 Williams Mar. 13, 1945 2,582,231 Catallo Jan. 15, 1952' 2,855,181 Olsen Oct. 7, 1958 2,998,088 Pennington Aug. 29, 1961 3,095,053 Pistole et al. June 25, 1963 FOREIGN PATENTS 1,249,346 Fnance Nov. 21, 1960 Attesting Officer NITED STATES PATENT oFFic Pa tent No. 3,153,458 Octo ber 20, 1964 Lot William Short,
It is hereby certified that error appears the above numbered patent requiring correction and thatthesaid Letters Patent should read'as corrected below. Y
' In the grant, lines 2 and 3, for "assignor .to Drilling 8: Service, Inc. of Detroit, Michigan, a corporation of' Delaware," read assignor to Drilling 8z Service, Inc. a wholly-owned subsidiary of WheelTrueing ,Tool' Company, of Detroit, Michigan a corporation of Delaware line 12, a for "Drilling 81 Service, Inc. its successors" read Drilling 8: Service, Inc. a wh oll.y-own.ed. subsidiary ofwheel Trueing Tool Company, its successors -,I;' inthe heading to the printed specification, lines 3 and 41, for "assignor to Drilling 81 Service, Inc. Detroit, Mich, 4a corp-oration of. Delaware" read assignor to Drilling 81 Service, Inc a wholly owned sudsidiary of Wheel Trueing .Tool Company, Detroit, Mich. a corporation of Delaware,
Signed and sealed this 20th day of April 1965.
EDWARD J. BRENNER Commissioner of Patents ERNEST W. SWIDER